Depssi Card

It is a handy guide/reference card that has two functions; it enables the ‘outdoor photographer’ to quickly select the ‘hyperfocal’ distance (see below) for different lenses (or zoom settings) using various apertures, and as a bonus, the reverse side of the card gives the angles/positions of sunrise and sunset for every month.
The card is made in a durable plastic suitable for prolonged use. The size of a credit card, it can be tucked into a wallet/purse or secured to your camera bag until needed.
(all Depssi cards are £3.20 each + p/p)

‘Depth Of Field’

The ‘depth of field,’(DOF) in a photograph is, as most photographers know, crucial to the final image. Usually, (although, not always) maximum ‘DOF’ is required for landscape photography to achieve ‘front to back’ sharpness. This is best achieved by focusing at the ‘hyperfocal’ distance.(everything from half the hyperfocal distance to infinity will be in focus!) The problem is, many camera lenses do not have sufficient markings to determine what that distance is. This distance changes, depending on the lens focal length, & f/stop(aperture) being used, and, just to complicate matters further, digital cameras(with sensors smaller than 35mm) differ again!
That’s why two cards have been produced:

The Mathematical equations
For those of you who might be interested, the equations used for the ‘Depssi’ cards are shown:
Hyperfocal distance= L2/(DxF) where L=lens focal length
D=diameter of the circle
Of least confusion
(0.029-for 35mm)
(0.019-for 1.5/1.6 digital)
F=aperture (f/stop)

e.g. using a 35mm SLR with a 24mm wide angle lens @ f/8

L2 =24x24=576

DxF=(0.029x8)=0.232

576/0.232=2482/1000= 2.4metres(approx)

If you focus at approx 2.4m, everything from half that distance (1.2m) to infinity will be in focus!

Sunrise/sunset

The sunrise/sunset indicator on the reverse side of the ‘Depssi’ card is useful for many outdoor photography situations. Knowing these positions can improve your chances of taking a great picture, immensely, and crucial for landscape buffs!
You may find when out at dawn shooting landscapes, you are able to determine using the Depssi card that sunset may give a better angle of lighting, or perhaps the angles will be more favourable in a few months time when you can return to capture that magical image!

True North
On o.s. maps you will find reference to three ‘Norths’.
1. True North
2. Magnetic North
3. Grid North

The ‘Depssi’ card ‘North arrow’ should be pointed towards TRUE North. Currently, True North, is approx 2-3 degrees east of Magnetic North. (Check your map for up-to-date information.)
Please note: The positions shown for the sun are given as averages for each month. (For British Isles use). They can differ by several degrees even within a four week period!

Cards may differ slightly from those shown as improvements are added.

Please note: The Depssi card should not be used as a navigational device.

The Depssi Card has had a few improvements made to widen its appeal. The sunrise/sunset angles, primarily designed for the U.K., are applicable to many other regions of the world which are indicated on the latest designs (cards 1&2). See list for more information. In addition, a brand new version for sunrise/set positions (cards 3&4) has been introduced to cover most of the U.S.A., the Mediterranean, Northern China and Japan. See list (and map of U.S.A.) for cards 3 and 4 for more detailed information.
Please note: if you purchased one of the original Depssi cards, the sun angles are the same as for new cards 1and 2.

Can be used: U.S.A.—anywhere between Minneapolis in the north and as far south as Los Angeles including New York, Denver, San Francisco, Washington D.C, St.Louis. Memphis. Also, Portugal, Spain, Southern France, Italy, Greece, Bulgaria, Turkey, Cyprus, Japan, Beijing, and coastal areas of Morocco, Algiers, and Tunisia.

Card 3(Front/Back)
*Green No:3

Green for 35mm and full frame digital SLRs

Card 4(Front/Back)
*Blue No:4

Blue for digital sensors of 1.5x and 1.6x

Map of U.S.A. Red band shows area of use for Cards 3 & 4
Of course, the hyperfocal charts can be used anywhere in the world!

F.A.Q.

Q. How accurate are the sun position angles?
A. Although the sunrise/set angles vary slightly each month, the cards show an average position and we have found the accuracy more than adequate for planning photo forays.

Q. And the hyperfocal charts?
A. The formulas used to indicate hyperfocal distances are based on photographic industry standards and are very accurate, and indeed can be rounded off in practice.

Q. Why not have more lens/aperture combinations for the hyperfocal charts?
A. With an information product the size of a credit card, available space is limited. I have chosen the most popular combinations where maximum depth of field is needed.

Q. The hyperfocal distances are given in metres, could you also provide a card in feet and yards?
A. No plans to produce cards in ft/yds as metric is more or less universal. However, if preferred, the conversions to feet can be marked on to the Depssi cards using a permanent fine tip marker, such as a CD writer pen.
(Multiply metres by 3.28 to give feet) e.g. 1.2m x 3.28= 4ft approx.

Q. Do I always need to use a compass with the Depssi card?
A. No! I often place my card on a map of the area I’m planning a shoot, and it is sufficient to point the red North arrow to the top of the map, the lines on the Depssi card will indicate the sunrise and sunset angles. Easy!
And if you are out taking photos at dawn you can simply point the sunrise line on the Depssi card towards the sun and the sunset line (for the relevant month) will indicate the position of the sun at dusk.(which may give a better angle of light). Of course, the procedure can also be done in reverse.

Q. Hyperfocal distances vary depending on the type of camera being used, how can I tell if a Depssi card can be used with my camera system?
A. The Green Depssi cards (nos. 1&3) are designed for 35mm SLRs and ‘full frame’ digital cameras.
The Blue Depssi cards (nos. 2&4) are designed for digital SLRs with cropped sensors of 1.5x and 1.6x.
Is your digital SLR compatible with a Blue card?........simply divide the equivalent focal length by the actual focal length.(these figures should be found in your camera instruction manual). With zoom lenses, use the minimum or maximum focal length figures indicated for your camera system.
E.g. if the equivalent focal length is 24mm and the actual is 16mm =
24÷16=1.5 in this example the cropped sensor is 1.5x.